The present invention relates, in general, to traffic control devices and, more particularly, to signal monitors and traffic control signals.
A traffic control assembly may include a flasher, a flash transfer relay, and a signal monitor and is used to control traffic at intersections. The signal monitor is a device used in the traffic control assembly to detect and respond to conflicting or otherwise improper signals. Such improper signals may arise, for example, due to field signal conflicts, a malfunctioning controller, faulty load switches, cabinet mis-wiring, improper supply voltages, and the like. The flasher is a device in the traffic control assembly that delivers power to the selected light source when operating in a flashing mode and flash transfer relays are used to switch the source of the traffic signal power from load switches to the flasher. When one or more failures occur, the signal monitor instructs (or causes other components to instruct) the signal lights to enter a “flash” mode, in which the traffic lights on all sides of the intersection generally enter a flashing red state or a flashing yellow state.
Accordingly, it would be advantageous to have improved signal monitor systems and methods that may diminish the possibility of vehicle operators encountering contradictory signals at, for example, an intersection in flash mode. It would be of further advantage for the signal monitor system and method to be cost efficient to implement.
It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action and the initial action. The use of the word approximately, about, or substantially means that a value of an element has a parameter that is expected to be very close to a stated value or position. However, as is well known in the art there are always minor variances that prevent the values or positions from being exactly as stated. For simplicity and clarity of illustration, the drawing figures depict the general topology, structure and/or manner of construction of the various embodiments.
Descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring other features. For example, conventional techniques and components related to traffic control devices are not described in detail herein. Elements in the figures are not necessarily drawn to scale: the dimensions of some features may be exaggerated relative to other elements to assist in understanding the example embodiments.
Terms of enumeration such as “first,” “second,” “third,” and the like may be used for distinguishing between similar elements and not necessarily for describing a particular spatial or chronological order. These terms, so used, are interchangeable under appropriate circumstances. The embodiments of the invention described herein are, for example, capable of use in sequences other than those illustrated or otherwise described herein. Unless expressly stated otherwise, “connected,” if used herein, means that one element/node/feature is directly joined to (or directly communicates with) another element/node/feature, and not necessarily mechanically. Likewise, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to (or directly or indirectly communicates with) another element/node/feature, and not necessarily mechanically.
The terms “comprise,” “include,” “have” and any variations thereof are used synonymously to denote non-exclusive inclusion. The terms “left,” “right,” “in,” “out,” “front,” “back,” “up,” “down,” and other such directional terms are used to describe relative positions, not necessarily absolute positions in space. The term “exemplary” is used in the sense of “example,” rather than “ideal.”